Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

From January 2018 to December 2024, 75% of Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%).

  • Total suspected cases: 39,805
  • Total confirmed cases: 6,003
  • Deaths from Confirmed Cases: 1,098
  • Case Fatality Ratio: 21%
  • Number of Health Care Workers: 232

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all lab confirmed cases in Nigeria was between 16-27% and decreased over time.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • The variation in CFR is likely due to late patient presentation and differences in case management, highlighting the need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 13

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 3,783 suspected cases were reported from 1 in Jigawa, Katsina, Osun to 1,149 in Edo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 29% decrease in the cumulative number of suspected cases reported.

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 18% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 13, 87% of LF cases are from Ondo (30%), Bauchi (25%), Edo (16%), and Taraba (16%) States.

  • Total confirmed cases: 659

  • Deaths from Confirmed Cases: 122

  • Case Fatality Ratio: 19%

  • Number of Health Care Workers: 20

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 13 2025, cumulatively 659 cases and 122 deaths (CFR=19%) across 18 States have been reported.
  • At same period 2024, a total of 27 States reported at least one confirmed cases.
  • There is a 29% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • There is a 18% decrease in the number of confirmed cases reported in 2025 compared to 2024.
  • In 2024,
    • 36 States had reported at least one suspected case versus 34 States in 2025 to date.
    • 27 States had reported at least one confirmed case versus 18 States in 2025 to date.

Health care worker infections 2020-2025 epiweek 13


  • Top 5 states:
    • 8 HCW infections in Ondo
    • 4 HCW infections in Bauchi
    • 2 HCW infections in Taraba
    • 2 HCW infections in Gombe
    • 1 HCW infections in Ebonyi.

  • As of epi week 13 of 2025, there has been 20 healthcare workers infected, that is 3% of confirmed cases.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 13)

Lassa fever in Ondo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ondo as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 1071 195 25 13%
2024 1106 192 13 7%
2023 1104 269 30 11%
2022 643 194 34 18%
2021 283 64 18 28%
2020 475 305 43 14%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ondo State reported 195 confirmed cases including 25 deaths (CFR 13%).
  • Compared to same period 2024, this represents:
    • 3% decrease in the number of suspected cases.
    • 2% increase in the number of confirmed cases.
    • 89% increase in CFR.




  • In 2024 as of week 13:
    • 1106 in the number of suspected cases.
    • 192 in the number of confirmed cases.
    • 13 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 13:
    • 1104 in the number of suspected cases.
    • 269 in the number of confirmed cases.
    • 30 in the number of deaths.
    • 11% average CFR.




  • In 2022 as of week 13:
    • 643 in the number of suspected cases.
    • 194 in the number of confirmed cases.
    • 34 in the number of deaths.
    • 18% average CFR.




  • In 2021 as of week 13:
    • 283 in the number of suspected cases.
    • 64 in the number of confirmed cases.
    • 18 in the number of deaths.
    • 28% average CFR.




  • In 2020 as of week 13:
    • 475 in the number of suspected cases.
    • 305 in the number of confirmed cases.
    • 43 in the number of deaths.
    • 14% average CFR.

Lassa fever in Bauchi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Bauchi as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 690 166 12 7%
2024 604 127 28 22%
2023 612 94 17 18%
2022 598 104 12 12%
2021 39 7 2 29%
2020 259 42 18 43%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Bauchi State reported 166 confirmed cases including 12 deaths (CFR 7%).
  • Compared to same period 2024, this represents:
    • 14% increase in the number of suspected cases.
    • 31% increase in the number of confirmed cases.
    • 67% decrease in CFR.




  • In 2024 as of week 13:
    • 604 in the number of suspected cases.
    • 127 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 22% average CFR.




  • In 2023 as of week 13:
    • 612 in the number of suspected cases.
    • 94 in the number of confirmed cases.
    • 17 in the number of deaths.
    • 18% average CFR.




  • In 2022 as of week 13:
    • 598 in the number of suspected cases.
    • 104 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 12% average CFR.




  • In 2021 as of week 13:
    • 39 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.




  • In 2020 as of week 13:
    • 259 in the number of suspected cases.
    • 42 in the number of confirmed cases.
    • 18 in the number of deaths.
    • 43% average CFR.

Lassa fever in Edo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Edo as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 1149 105 16 15%
2024 1236 179 23 13%
2023 1499 243 31 13%
2022 1166 167 21 13%
2021 888 102 12 12%
2020 1049 309 39 13%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Edo State reported 105 confirmed cases including 16 deaths (CFR 15%).
  • Compared to same period 2024, this represents:
    • 7% decrease in the number of suspected cases.
    • 41% decrease in the number of confirmed cases.
    • 19% increase in CFR.




  • In 2024 as of week 13:
    • 1236 in the number of suspected cases.
    • 179 in the number of confirmed cases.
    • 23 in the number of deaths.
    • 13% average CFR.




  • In 2023 as of week 13:
    • 1499 in the number of suspected cases.
    • 243 in the number of confirmed cases.
    • 31 in the number of deaths.
    • 13% average CFR.




  • In 2022 as of week 13:
    • 1166 in the number of suspected cases.
    • 167 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 13% average CFR.




  • In 2021 as of week 13:
    • 888 in the number of suspected cases.
    • 102 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 12% average CFR.




  • In 2020 as of week 13:
    • 1049 in the number of suspected cases.
    • 309 in the number of confirmed cases.
    • 39 in the number of deaths.
    • 13% average CFR.

Lassa fever in Taraba State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Taraba as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 260 105 31 30%
2024 196 95 20 21%
2023 223 79 26 33%
2022 74 29 14 48%
2021 47 18 11 61%
2020 94 55 21 38%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Taraba State reported 105 confirmed cases including 31 deaths (CFR 30%).
  • Compared to same period 2024, this represents:
    • 33% increase in the number of suspected cases.
    • 11% increase in the number of confirmed cases.
    • 40% increase in CFR.




  • In 2024 as of week 13:
    • 196 in the number of suspected cases.
    • 95 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 21% average CFR.




  • In 2023 as of week 13:
    • 223 in the number of suspected cases.
    • 79 in the number of confirmed cases.
    • 26 in the number of deaths.
    • 33% average CFR.




  • In 2022 as of week 13:
    • 74 in the number of suspected cases.
    • 29 in the number of confirmed cases.
    • 14 in the number of deaths.
    • 48% average CFR.




  • In 2021 as of week 13:
    • 47 in the number of suspected cases.
    • 18 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 61% average CFR.




  • In 2020 as of week 13:
    • 94 in the number of suspected cases.
    • 55 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 38% average CFR.

Lassa fever in Ebonyi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ebonyi as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 104 20 9 45%
2024 223 43 24 56%
2023 173 50 28 56%
2022 186 37 17 46%
2021 79 15 6 40%
2020 176 72 20 28%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ebonyi State reported 20 confirmed cases including 9 deaths (CFR 45%).
  • Compared to same period 2024, this represents:
    • 53% decrease in the number of suspected cases.
    • 53% decrease in the number of confirmed cases.
    • 19% decrease in CFR.




  • In 2024 as of week 13:
    • 223 in the number of suspected cases.
    • 43 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 56% average CFR.




  • In 2023 as of week 13:
    • 173 in the number of suspected cases.
    • 50 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 56% average CFR.




  • In 2022 as of week 13:
    • 186 in the number of suspected cases.
    • 37 in the number of confirmed cases.
    • 17 in the number of deaths.
    • 46% average CFR.




  • In 2021 as of week 13:
    • 79 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2020 as of week 13:
    • 176 in the number of suspected cases.
    • 72 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 28% average CFR.

Lassa fever in Kogi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Kogi as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 64 15 4 27%
2024 102 28 2 7%
2023 35 11 1 9%
2022 99 38 7 18%
2021 5 1 0 0%
2020 79 34 8 24%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Kogi State reported 15 confirmed cases including 4 deaths (CFR 27%).
  • Compared to same period 2024, this represents:
    • 37% decrease in the number of suspected cases.
    • 46% decrease in the number of confirmed cases.
    • 273% increase in CFR.




  • In 2024 as of week 13:
    • 102 in the number of suspected cases.
    • 28 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 13:
    • 35 in the number of suspected cases.
    • 11 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 9% average CFR.




  • In 2022 as of week 13:
    • 99 in the number of suspected cases.
    • 38 in the number of confirmed cases.
    • 7 in the number of deaths.
    • 18% average CFR.




  • In 2021 as of week 13:
    • 5 in the number of suspected cases.
    • 1 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 13:
    • 79 in the number of suspected cases.
    • 34 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 24% average CFR.

Lassa fever in Gombe State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 58 12 6 50%
2024 25 3 1 33%
2023 30 6 0 0%
2022 106 15 6 40%
2021 3 0 0 –
2020 27 7 2 29%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 12 confirmed cases including 6 deaths (CFR 50%).
  • Compared to same period 2024, this represents:
    • 132% increase in the number of suspected cases.
    • 300% increase in the number of confirmed cases.
    • 50% increase in CFR.




  • In 2024 as of week 13:
    • 25 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 33% average CFR.




  • In 2023 as of week 13:
    • 30 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2022 as of week 13:
    • 106 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2021 as of week 13:
    • 3 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 13:
    • 27 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.

Lassa fever in Benue State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Benue as of week 13:
Years Suspected cases Confirmed cases Deaths CFR
2025 61 9 4 44%
2024 1027 62 11 18%
2023 134 36 3 8%
2022 188 30 8 27%
2021 13 3 0 0%
2020 27 8 3 38%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Benue State reported 9 confirmed cases including 4 deaths (CFR 44%).
  • Compared to same period 2024, this represents:
    • 94% decrease in the number of suspected cases.
    • 85% decrease in the number of confirmed cases.
    • 151% increase in CFR.




  • In 2024 as of week 13:
    • 1027 in the number of suspected cases.
    • 62 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 18% average CFR.




  • In 2023 as of week 13:
    • 134 in the number of suspected cases.
    • 36 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 8% average CFR.




  • In 2022 as of week 13:
    • 188 in the number of suspected cases.
    • 30 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 27% average CFR.




  • In 2021 as of week 13:
    • 13 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 13:
    • 27 in the number of suspected cases.
    • 8 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 38% average CFR.

Thank you

Any questions or suggestions? Contact us: Anaïs Legand and Antoine Chaillon